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Exams400-007Questions#112
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400-007 · Question #112

400-007 Question #112: Real Exam Question with Answer & Explanation

The correct answer is C: low-latency queuing. Real-time applications require strict priority queuing to guarantee bounded latency and jitter. Low-Latency Queuing is the only listed mechanism that provides a dedicated strict-priority queue for time-sensitive traffic.

Question

Company XYZ is redesigning their QoS policy. Some of the applications used by the company are real- time applications. The QoS design must give these applications preference in terms of transmission. Which QoS strategy can be used to fulfill the requirement?

Options

  • Aweighted fair queuing
  • Bweighted random early detection
  • Clow-latency queuing
  • Dfirst-in first-out

Explanation

Real-time applications require strict priority queuing to guarantee bounded latency and jitter. Low-Latency Queuing is the only listed mechanism that provides a dedicated strict-priority queue for time-sensitive traffic.

Common mistakes.

  • A. Weighted Fair Queuing distributes bandwidth proportionally among active flows but provides no strict priority queue, so real-time traffic still experiences variable and potentially high delay during congestion.
  • B. Weighted Random Early Detection is a congestion-avoidance tool that preemptively drops TCP segments to prevent queue saturation, but it does not prioritize or provide low-latency treatment for real-time traffic classes.
  • D. First-In First-Out processes all packets in strict arrival order with no traffic classification or differentiation, offering no preferential treatment for delay-sensitive real-time applications.

Concept tested. Low-Latency Queuing priority for real-time traffic

Reference. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/qos_plcshp/configuration/xe-16/qos-plcshp-xe-16-book/qos-plcshp-oview.html

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